Metallic containers offer distributors and consumers many benefits by providing optimal protection properties for products. For example, metallic containers prevent CO2 migration and block UV radiation which can have a damaging effect on personal care, pharmaceutical, and food products and on other UV-sensitive formulations, negatively influencing the effectiveness of ingredients, as well as the fragrance, appearance, flavor, or color of the product. Metallic containers also offer an impermeable barrier to light, water vapor, oils and fats, oxygen and micro-organisms and keep the contents of the container fresh and protected from external influences, thereby guaranteeing a long shelf-life.
The increased durability of metallic containers compared to glass containers reduces the number of containers damaged during processing and shipping, resulting in further savings. Additionally, metallic containers are lighter than glass containers of comparable size, resulting in energy savings during shipment. Further, metallic containers can be manufactured with high burst pressures which make them ideal and safe for use as containers holding products under pressure, such as aerosol containers. Finally, recycling metallic containers is generally easier than recycling glass and plastic containers because labels and other indicia are printed directly onto the metallic body of the container while glass and plastic containers typically have labels that must be separated during the recycling process.
Metallic containers may include a container body that is formed in a draw and wall ironing (DWI) process separately from a can end. The manufacture of the DWI container body starts by forming a cup from a metallic stock material which is typically shipped and stored in large rolls. Referring to FIG. 1, which depicts the prior art process, a sheet 4 of metallic stock material is fed into a draw-redraw apparatus 2. As shown in FIG. 1A, a blank and draw die 6 cuts a blank 8 from the sheet 4. The blank 8 can have any desired shape. The cut blank 8 is illustrated in FIG. 1A separate from apparatus 2 for clarity. The blank and draw die 6 then draws the blank 8 into a cup 9 with sidewalls 10 and a closed endwall 11 with a first diameter, as illustrated in FIG. 1B. Referring now to FIGS. 1C-1D, optionally a redraw die 12 redraws the cup 9 into a formed cup 13 with a closed endwall 14. As will be appreciated by one of skill in the art, during a redraw operation, the direction of the sidewalls 15 of the cup 14 are reversed. Thus, the open end of the cup 13 faces a direction substantially opposite of the direction of the open end of cup 9. The redraw operation also generally lengthens the sidewalls 15 compared to sidewalls 10 of cup 9, reducing the diameter of the closed endwall 14. Thus, the endwall 14 of the formed cup 13 has a second diameter that is less than the first diameter. The formed cup 13 is then ejected from the apparatus 2 and another portion of the sheet 4 is fed into the apparatus 2, as illustrated in FIG. 1E. In the prior art apparatus 2 illustrated in FIG. 1, the formed cup 13 has a cross-section with generally linear sidewalls 15, as shown in FIG. 1D. The closed endwall 14 is also generally linear. After forming the cup 13, the apparatus 2 ejects the cup in a direction substantially perpendicular to the sheet 4 of stock material. The formed cup 13 is subsequently formed into a container body by a bodymaker by methods known to those of skill in the art. Generally, the size of the container body is directly related to the size of the blank 8 used to form the formed cup 13, i.e., the larger the blank, the more material that is present to form the formed cup 13 and, subsequently, the container body.
To form a taller or wider container body, such as an aerosol container, current manufacturing methods require a blank of a larger size resulting in a formed cup 13 with an increased height. For example, to form a taller or wider container body using the method and apparatus of FIGS. 1A-1E, the height of the sidewall 15 of the formed cup 13 is increased. However, as the height of the formed cup increases, the bodymaker must use a longer punch stroke and longer stroke redraw carriage to form the formed cup 13 into the container body, reducing the speed and efficiency of the bodymaker.
Accordingly, there is an unmet need for a method and apparatus of forming a cup from a blank with a larger size without increasing the height of the cup so that the cup can be reformed into a larger container body without reducing the speed and efficiency of a conventional bodymaker. Further, by utilizing conventional bodymaker tools, equipment costs can be reduced because new tooling is not required in the manufacturing plant. The present invention is particularly useful to manufacture metallic cups which can be utilized in a bodymaker to form aerosol containers.